haresources defines the action if a machine goes down.
If machine(A|B) notices machine(B|A) is down, it'll use the "MailTo" resource (in /etc/ha.d/resource.d/) to send a warning email to admin@domain.be

Logfacility : log messages will be sent to /var/log/messages
keepalive : 5 seconds between checks
deadtime : how long before it declares the other host down
warntime : how long it takes before sending the warning
ucast : if cross-monitoring machines, use unicast which is less disruptive, else, use "bcast ethX"
node : specify the nodes to monitor